High density disk unit and disk medium

Abstract

A high-density disk unit and disk medium are disclosed. Track ID information is not placed in a servo area, or if some track ID information is placed therein, a necessary minimum is placed. The servo area is thus reduced in order to improve formatting efficiency. A data side of a disk medium is divided into a servo area and a data area in units of a sector. A track ID area in which track information is recorded is defined at the start position of the data area immediately following the servo area. A formatter circuit allows a write data modulation circuit to write track information in the track ID area during track formatting. For writing in the data area, the formatter circuit allows a read data demodulation circuit to read data from the track ID area. Track information is thus detected, and writing tracking is assured.

We claim: 
     
       1. A disk unit comprising: a disk medium having at least one data side which is divided into a plurality of information areas each having a servo area and a data area in a track direction, said data area having a plurality of data blocks and a track ID area in which track information including a first part of a cylinder address is recorded immediately following each said servo area, said servo area having a track ID area that has only a second part of a cylinder address;   a servo demodulation circuit for demodulating head position information from a read signal recorded in said servo area;   a write data modulation circuit for modulating write data and writing it in said data area; and   a formatter circuit that allows said write data modulation circuit to write track information in said track ID area within said data area during track formatting, and allows said read data demodulation circuit to read data from said track ID area within said data area and to detect track information for writing or reading.   
     
     
       2. A disk unit according to claim 1 wherein: said servo area includes a recovery area used to switch between reading and writing, a servo mark area in which a servo mark indicating a servo area is recorded, an area in which an AGC pattern used for AGC control of a read signal is recorded, and a position detection area in which a two-phase servo pattern used to detect a head position is recorded; and   said track ID area of said data area includes a PLL synchronization control area used to synchronize the oscillatory frequency of a read clock with the rotation of a disk, a sync byte area in which a synchronization pattern used to synchronize read data with said read clock is recorded, and a track information recording area in which track address information is recorded.   
     
     
       3. A disk unit according to claim 1 wherein said second part of said cylinder address includes gray codes representing low-order bits of said cylinder address and said first part of said cylinder address includes remaining bit data, said gray codes being recorded in said second track ID area and said remaining bit data being recorded in said track ID area within said data area. 
     
     
       4. A disk unit according to claim 1 wherein: said servo area includes a training area in which a synchronization pattern used to synchronize a read signal in phase with a reference clock oscillator is recorded, a marker area in which a marker indicating a specific position within said servo area is recorded, and a position detection area in which a phase servo pattern is recorded; and   said track ID area within said data area includes a PLL synchronization control area used to synchronize the oscillatory frequency of a read clock with the rotation of a disk, a sync byte area in which a synchronization pattern used to synchronize read data with said read clock is recorded, and a track information recording area in which track address information is recorded.   
     
     
       5. A disk unit according to claim 1 further comprising a head unit having a write head, and a read head disposed a certain distance from said write head with respect to the center of a track which defines a mismatch of a center of said write head relative to a center of said read head, wherein said formatter circuit off-tracks said write head toward said read head by the magnitude of said mismatch, so that said write head is then aligned to write said track information.   
     
     
       6. A disk unit according to claim 5 wherein when formatting a plurality of tracks sequentially, said formatter circuit positions a head unit on a track to be formatted, measures the magnitude of said mismatch, off-tracks said write head toward said read head by said measured magnitude of said mismatch, and then writes track information in said track ID area. 
     
     
       7. A disk unit according to claim 6 wherein measurement of the magnitude of said mismatch by said formatter circuit is such that: first, a write head is used to write measurement data on a track; then said write head is changed into a read head; an off-track is varied in units of a very small magnitude, and the magnitude of an offtrack detected when a read signal of a peak value is obtained is measured as the magnitude of the mismatch. 
     
     
       8. A disk medium having at least one data side which is divided into servo-area and data area units, each said data area unit having a plurality of data blocks, wherein a track ID area having track information including a first part of a cylinder address is located in the data area associated with each said servo area, and each said servo area includes a track ID area in which only a second part of said cylinder address is recorded. 
     
     
       9. A disk medium according to claim 8 wherein: said servo area includes a recovery area used to switch between reading and writing, a servo mark area in which a servo mark indicating a servo area is recorded, an area in which an AGC pattern used for AGC control of a read signal is recorded, and a position detection area in which a two-phase servo pattern used to detect a head position is recorded; and   said track ID area within said data area includes a PLL synchronization control area used to synchronize the oscillatory frequency of a read clock with the rotation of a disk, a sync byte area in which a synchronization pattern used to synchronize read data with said read clock is recorded, and a track information recording area in which track address information is recorded.   
     
     
       10. A disk medium according to claim 8 wherein said track information is a cylinder address divided into gray codes representing low-order bits of said track address and remaining bit data of said track address, said gray codes being recorded on said track ID area within said servo area and said remaining bit data being recorded on said track ID area within said data area. 
     
     
       11. A disk medium according to claim 8 wherein said servo area includes a training area in which a synchronization pattern used to synchronize in phase a reference clock oscillator in a disk unit with a read signal is recorded, a marker area in which a marker indicating a specific position within said servo area is recorded, and a position detection area in which a phase servo pattern is recorded, and said track ID area within said data area includes a PLL synchronization control area used to synchronize the oscillatory frequency of a read clock with the rotation of a disk, a sync byte area in which a synchronization pattern used to synchronize read data with said read clock is recorded, and a track information recording area in which track address information is recorded.   
     
     
       12. A disk medium according to claim 8 further comprising a head unit having a write head, and a read head disposed a certain distance from said write head, said distance defining a magnitude of a mismatch, wherein said track identification information is recorded by off-tracking a write head toward a read head with respect to the center of a track by the magnitude of said mismatch. 
     
     
       13. A disk unit comprising: a disk medium having at least one data side which is divided into a plurality of information areas each having a servo area and a data area in a track direction, said data area having a track ID area in which track information including a cylinder address is recorded immediately following each said servo area, said track information only being recorded in each said data area;   a servo demodulation circuit for demodulating head position information from a read signal recorded in said servo area;   a write data modulation circuit for modulating write data and writing it in said data; and   a formatter circuit that allows said write data modulation circuit to write track information in said track ID area during track formatting, and allows said read data demodulation circuit to read data from said track ID area and to detect track information for writing or reading.   
     
     
       14. A disk unit according to claim 13 wherein: said servo area includes a recovery area used to switch between reading and writing, a servo mark area in which a servo mark indicating a servo area is recorded, an area in which an AGC pattern used for AGC control of a read signal is recorded, and a position detection area in which a two-phase servo pattern used to detect a head position is recorded; and   said track ID area includes a PLL synchronization control area used to synchronize the oscillatory frequency of a read clock with the rotation of a disk, a sync byte area in which a synchronization pattern used to synchronize read data with said read clock is recorded, and a track information recording area in which track address information is recorded.   
     
     
       15. A disk unit according to claim 13 wherein: said servo area includes a training area in which a synchronization pattern used to synchronize a read signal in phase with a reference clock oscillator is recorded, a marker area in which a marker indicating a specific position within said servo area is recorded; and a position detection area in which a phase servo pattern is recorded; and   said track ID area includes a PLL synchronization control area used to synchronize the oscillatory frequency of a read clock with the rotation of a disk, a sync byte area in which a synchronization pattern used to synchronize read data with said read clock is recorded, and a track information recording area in which track address information is recorded.   
     
     
       16. A disk unit according to claim 13 further comprising a head unit having a write head, and a read head disposed a certain distance from said write head with respect to the center of a track which defines a mismatch of a center of said write head relative to a center of said read head, wherein said formatter circuit off-tracks said write head toward said read head by the magnitude of said mismatch, so that said write head is then aligned to write said track information.   
     
     
       17. A disk unit according to claim 16 wherein when formatting a plurality of tracks sequentially, said formatter circuit positions a head unit on a track to be formatted, measures the magnitude of said mismatch, off-tracks said write head toward said read head by said measured magnitude of said mismatch, and then writes track information in said track ID area. 
     
     
       18. A disk unit according to claim 17 wherein measurement of the magnitude of said mismatch by said formatter circuit is such that: first, a write head is used to write measurement data on a track; then said write head is changed into a read head; an off-track is varied in units of a very small magnitude, and the magnitude of an off-track detected when a read signal of a peak value is obtained is measured as the magnitude of the mismatch. 
     
     
       19. A disk medium having at least one data side which is divided into servo area and data area units, wherein a track ID area having track information including a cylinder address is recorded only in the data area associated with each said servo area. 
     
     
       20. A disk medium according to claim 19 wherein: said servo area includes a recovery area used to switch between reading and writing, a servo mark area in which a servo mark indicating a servo area is recorded, an area in which an AGC pattern used for AGC control of a read signal is recorded, and a position detection area in which a two-phase servo pattern used to detect a head position is recorded; and   said track ID area includes a PLL synchronization control area used to synchronize the oscillatory frequency of a read clock with the rotation of a disk, a sync byte area in which a synchronization pattern used to synchronize read data with said read clock is recorded, and a track information recording area in which track address information is recorded.   
     
     
       21. A disk medium according to claim 19 wherein said servo area includes a training area having a synchronization pattern used to synchronize in phase a reference clock oscillator in a disk unit with a read signal is recorded, a marker area in which a marker indicating a specific position within said servo area is recorded, and a position detection area in which a phase servo pattern is recorded, and said track ID area includes a PLL synchronization control area used to synchronize the oscillatory frequency of a read clock with the rotation of a disk, a sync byte area in which a synchronization pattern used to synchronize read data with said read clock is recorded, and a track information recording area in which track address information is recorded.   
     
     
       22. A disk medium according to claim 19 further comprising a head unit having a write head, and a read head disposed a certain distance from said write head, said distance defining a magnitude of a mismatch, wherein said track identification information is recorded by off-tracking a write head toward a read head with respect to the center of a track by the magnitude of said mismatch.